1. Field of the Invention
The present invention relates to a polymerization catalyst which selectively gives trans- or cis-1,4-polybutadiene and a process for selective production of trans- or cis-1,4-polybutadiene using said catalyst.
In more particular, the present invention relates to a catalyst comprising a transition metal compound and an organoaluminum compound, to a process which gives a butadiene compound polymer wherein at least 50%, usually 60-90%, and under suitable polymerization conditions at least 90%, of the butadiene units contained therein are linked in trans-1,4-configuration by using said catalyst, and to a process for production of a butadiene compound polymer which gives a polybutadiene wherein at least 90% of the butadiene units contained therein are linked in cis-1,4-configuration by using a catalyst comprising a titanium compound, an aluminoxane and an organic compound having at least two hydroxyl groups.
2. Description of the Prior Art
Various processes are so far known for production of diene compound polymers, including radical polymerization, cationic polymerization, anionic polymerization, and coordinated anionic polymerization which uses Ziegler-Natta catalysts. As for systems which give trans-1,4-polybutadiene, there are known, for example, those reported by Natta et al. including the one which uses TICl.sub.3 of a solid catalyst and triethylaluminum (Gazzetta chimica Italiana, 89, 761 (1959)) and the one which uses soluble VCl.sub.4 and triethylaluminum (La Chimica e Industria, 41, 116 (1959)). However, these disclosed processes have the disadvantage of low catalytic activity and hence being unsuitable for use in the commercial production.
As for processes for production of polybutadiene having a high cis-1,4 content, there are known (1) a polymerization process which uses a catalyst comprising a trialkylaluminum and titanium tetraiodide (BE 551,851); (2) a polymerization process which uses a catalyst system comprising triisobutylaluminum and titanium tetrabromide (GB 824,201); (3) a polymerization process which uses a catalyst system comprising cobalt chloride and an organometallic compound (BE 573,680); (4) a process which uses a catalyst system comprising triethylaluminum, nickel naphthenate and boron trifluoride (Japanese Patent Application Kokoku (Post-Exam. Publn.) No. 3708198); (5) a process which uses a catalyst comprising tetrabenzyltitanium and methylaluminoxane, and other processes.
Among these processes, the process (5) has the disadvantage of low catalytic activity and hence being difficultly used for the commercial production [(Macromolecules) 22,2126, 1989]. The processes (1), (2) and (3), which use a transition metal catalyst system, are disadvantageous in that the catalyst cannot be removed sufficiently from the polymer formed.